The present invention relates to a sensing system having multiple wireless sensor terminals.
In recent years, with the progress of IoT (Internet of Things) called mono Internet, businesses and services over communication are diversified and various devices and services are connected to each other over a network.
Even in control systems for important infrastructure and industries, there is a trend to streamline the monitoring of devices to be controlled (motors, pumps, generators, and so on) which are operating and the operation of the control systems by controlling the devices over the network, or acquiring data of sensors that are installed in the devices and observe surrounding situations over the network.
In order to monitor existing production equipment and others over the network, wireless sensor terminals that do not require power wiring and communication wiring are installed at various places, thereby being capable of monitoring and controlling the existing production equipment over the network.
Since wireless sensor terminals receive a power supply from batteries or small power generation devices, there is a need to reduce power consumption in order to operate for a long period of time. For that reason, there has been known a technique in which a granularity of sensor data transmitted by the wireless sensor terminals is changed according to a state of a monitoring target to reduce the power consumption (for example, Japanese Unexamined Patent Application Publication No. 2016-163242).
Japanese Unexamined Patent Application Publication No. 2016-163242 discloses the technique in which a server transmits a collection rule to a gateway and the gateway controls the granularity of the sensor data so as to satisfy the collection rule when an abnormality or a presage of abnormality occurs in the monitoring target.
In addition, a technique has also been known in which when a large number of wireless sensor terminals are connected to the gateway that collects the sensor data, in order to reduce an excessive traffic of the wireless network, the wireless sensor terminal processes the sensor data and then transmits the processed sensor data to the gateway (for example, Japanese Unexamined Patent Application Publication No. 2017-41159).
Japanese Unexamined Patent Application Publication No. 2017-41159 discloses the technology in which after the measured sensor data is subjected to a predetermined process to compress a data size, the compressed data size is transmitted to an analysis unit of the sensor data to transfer the sensor data under a limited transfer capacity.